It is proposed to improve understanding of some of the earliest steps in androgen action. The hypothesis that androgen action results from the net effect of several free plasma androgens will be tested. A "total plasma androgenicity index" will be quantitated as the sum of the product of a) the mean total plasma concentration, b) the unbound fraction, and c) the inherent androgenic potency of the androgens. A. Specific, relatively simple radioimmunoassays will be developed for the measurement of the major plasma androgens--the 17 beta-hydroxysteroids (testerone, dihydrotestosterone, delta 5-androstenediol, and 3 alpha/ 3 beta-androstanediols) and 17-ketosteroids (androstenedione and dehydroepiandrosterone). The variability of the plasma levels of these androgens will then be established so that the mean plasma level of each may be measured. B. The percentage of each plasma androgen which is unbound (free) under physiologic conditions will be determined. C. The inherent potency of each androgen will be determined from studies in two, different, isolated cell systems. The rate of dihydrotestosterone formation and nuclear translocation from precursors will be compared in rat prostate minces. The efficacy of androgens in stimulating progestin secretion by cultured rat granulosa cells will be compared. The index will be applied to subtle virilizing disorders, such as male-pattern hirsutism in women, in order to test the hypothesis. Whether estradiol is inherently antiandrogenic will be tested in cultured granulosa cells. Some determinants of androgen entry into the blood stream will be studied. The possibility that a significant portion of the high androgen levels of hirsute and/or obese women arise from enhanced peripheral conversion from secreted precursors will be tested using in vivo isotopic infusion techniques. The hypothesis that subtle hyperandrogenism may result from variations in adrenocortical enzyme activity will be tested by measuring precursor/product ratios in plasma before and after ACTH stimulation. The hypothesis that LH is insensitive to modest decrements of plasma testosterone will be tested by acutely lowering plasma testosterone levels in normal volunteers with aminoglutethimide.